An integrated framework to bridge and map flood risks and human health risks from contaminated floodwaters during urban flooding episodes

Código

I-EBHE0062

Autores

Mohit Prakash Mohanty, Rahul Deopa

Tema

WG 1.04: From local to large scale human-water dynamics

Resumo

Urban flood events and their associated impacts have escalated significantly over several regions worldwide. Densely populated cities in India, such as New Delhi, Mumbai, Surat, Kolkata, Chennai, and Bangalore have been at the receiving end of incurring mammoth economic losses and human mortalities during concurrent urban flood events. Apart from these impacts, there is a highly sensitive but often overlooked concern associated with public health emerging from polluted flood waters. Most often, the contaminated floodwaters are the habitat of spreading diseases such as malaria and dengue in the form of epidemic outbreaks. Although process-based numerical models have advanced our understanding of the hydrological risks from urban floods, the human-health risk dimension is less explored. With several studies advocating on the adverse impacts of climate and socio-economic changes on urban flooding patterns, it is vital to identify suitable solutions and mitigation strategies to protect vulnerable communities from compound impacts of flood risks (Fr) and human health risks (Hr) from urban flooding. The present study proposes an integrated framework through hydrodynamic-cum-water quality modeling to quantify and map Fr and Hr under changing climate and socio-economic patterns. The integrated approach is demonstrated in New Delhi (India), infamous for urban flooding and outbreaks of diseases during every peak monsoon period. Historical and Future rainfall projections from CORDEX under RCPs 4.5 and 8.5 are statistically downscaled, while SSPs 1 and 3 scenarios from the CMIP6 consortium are considered to account for future socio-economic scenarios. A set of flood inundation (depth, velocity, and inundated area) and hazard maps are generated from the MIKE+ FLOOD model, an acclaimed 1D-2D coupled hydraulic model. The model runs are calibrated and validated for 2013 and 2023 flood events. The simulated outputs from MIKE+ FLOOD is fed to the MIKE + Eco-Lab water quality model to map the water quality dynamics and the spread of Fecal Indicator Bacteria (FIB). The Hr from FIBs is estimated based on the ?-Poisson dose-response model. This study develops a composite risk-information map showing the severity of hydrological extremes and human health risks. Our results indicate that immediate floodplains near the Yamuna River face severe Fr and Hr, while densely populated spots in the right banks face elevated levels of Hr. The proposed framework of fusing climate and socio-economic structures within a hydrodynamic-cum-water quality modeling environment is generic as it promises its application for any other flood-affected city. The study recommends efficient resilience and adaptation options to safeguard communities at risk, especially in the developing and underdeveloped nations that face increasing flooding and public health concerns with concomitant climate change and socio-economic changes.